There may be numerous applications for a force feedback interface in dexterous task simulations, in which it may be desirable to control forces on independent fingers. A number of haptic devices have been devised that attempt to create the feeling of grasping an object by fingers and hand.
Some haptic devices may be capable of providing force feedback to all five fingers. For example, an exoskeleton may be worn over a glove, which may provide measurement information about hand gestures, through several embedded sensors that register the motion at various joints. A host computer may recognize the position of the hand and fingers with respect to a virtual object being approached. The computer may perform collision detection, and send resulting forces to a force control unit that may have a servomotor for each finger. For each finger, a sheathed cable may connect the finger tip through cable guide bridges to a pulley mounted on a motor shaft. The motor rotation may be controlled by setting the effective cable length to be such that the finger is stopped when its virtual counterpart touches the virtual object.
These haptic devices may be quite costly, and may suffer from system complexity. Users of these haptic devices may be inconvenienced by the requirement of an additional sensor glove. The mechanical bandwidth of these devices may be quite low, resulting in an unrealistic feeling of grasp. Forces may be unrealistically exerted on the back of the fingers and hand as well, when a virtual object is held, due to cable guide bridges mounted on the back of fingers. Also, these haptic devices may provide force feedback on finger tips only, so that holding a ball may give the same feeling as holding a disk, for instance. This may limit their applicability.